A process of manufacturing semiconductor substrates (hereinafter, simply referred to as “substrates”) conventionally involves various types of processing that is performed on substrates by various types of substrate processing apparatuses. For example, processing such as etching is performed on a surface of a substrate having a resist pattern on the surface thereof, by supplying a chemical solution to the substrate. After the etching process ends, other processing is also performed, such as supplying a removing liquid to the substrate to remove a resist from the substrate or supplying a cleaning liquid to the substrate to clean the substrate.
In the case where the processing of substrates is performed in an environment in which oxygen exists (e.g., in the air), oxygen may adversely affect the substrates. For example, oxygen may be dissolved in a chemical solution that is used in processing, and this chemical solution may adversely affect a surface of a substrate due to coming in contact with the surface of the substrate. In particular, in the processing of a substrate having a metal film on the surface, the metal film may oxidize during processing. It is sought to avoid such oxidation of the metal film as much as possible.
A substrate processing apparatus disclosed in Japanese Patent Application Laid-Open No. 2010-56218 (Document 1) includes a shield part that opposes a substrate held by a substrate holding mechanism. The shield part includes a substrate opposing surface that opposes the upper surface of the substrate, and a peripheral wall part that protrudes toward the substrate holding mechanism from the periphery of the substrate opposing surface. The substrate receives supply of a chemical solution that is a mixture of inert gas-dissolved water with low oxygen concentration and an undiluted chemical solution. The shield part provided in the substrate processing apparatus of Document 1 allows the atmosphere above the upper surface of the substrate to be cut off from the outside atmosphere and suppresses an increase in the oxygen concentration in the atmosphere above the substrate. Reducing the oxygen concentration above the substrate, for example, suppresses oxidation of the metal film provided on the upper surface of the substrate.
Incidentally, in the substrate processing apparatus of Document 1, the inside and outside of the shield part are not completely isolated from each other, and thus there is a limit to reducing the oxygen concentration in the atmosphere above the substrate. There is also a limit to quickly reducing the oxygen concentration within the shield part. On the other hand, it is conceivable to provide a substrate holder and a processing-liquid supply part within a chamber (treatment chamber) and to create a low oxygen condition in the chamber by sealing the chamber after the substrate is conveyed in the chamber and supplying an inert gas or the like to the internal space of the chamber. However, it takes a certain amount of time to create a sufficiently low oxygen condition in the internal space of the chamber.